Ten-year-old Matthew Oldman of Prestwich in Greater Manchester had a birthday surprise to beat them all recently - a telegram of congratulations from HR the Queen.
He didn't immediately spot the error, wishing him a Happy 100th Birthday, and excitedly showed the card to his mum and dad.
"We realised straight away what had happened", said his father, Dirky, a road sweeper, "but this sort of thing isn't on!"
Buckingham Palace officials apologised for the gaffe, saying that it was down to a computer error.
"Our software, like the Royal Family itself, is outdated", said Ronald Treason, who was then whisked away to the Tower of London for an early-afternoon beheading.
Experts say the Palace database misread Matthew's age as 100 instead of 10, the mistake being compounded by his surname.
"It's a freak accident", said analyst John Elton, "a bit like Camilla Barker Powles", before he, too, was arrested.
Yesterday, Matthew was unavailable for comment after consulting his solicitor about filing for a £100million lawsuit against the Royals.
Sue Yorass of Yorass, Hisass & Therass Solicitors said, "Matthew has suffered incalculably over this birthday blunder. He deserves some recompense, and we intend to get our cut."